An electric grid having high impedance seen from the connection point is considered as a weak grid and it adversely affects the system stability of grid-tied voltage source inverters in renewable power devices. In this study, an adaptive controller is proposed by configuring the settling time of the phase-locked loop based on the estimated grid impedance. Pseudorandom binary sequence injection and Fourier techniques are carried out for grid impedance estimation. Impedance-based stability analysis is performed for a predetermined steady-state operation point. The proposed method is verified by a 300-kVA inverter prototype for wide-range grid impedance varying from 0.3 to 3 mH.

中文翻译：

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基于电网阻抗估计的自适应控制器，可在弱电网条件下稳定并网逆变器的运行

从连接点看具有高阻抗的电网被认为是弱电网，并且它不利地影响可再生电力装置中并网电压源逆变器的系统稳定性。在这项研究中，通过基于估计的电网阻抗配置锁相环的建立时间，提出了一种自适应控制器。进行了伪随机二进制序列注入和傅立叶技术来估计电网阻抗。针对预定的稳态操作点执行基于阻抗的稳定性分析。300 kVA逆变器原型针对0.3至3 mH的宽范围电网阻抗验证了该方法的有效性。